1. Field of the Invention
The present invention relates to an image display apparatus.
2. Description of the Related Art
Generally, image display apparatuses include a function for adjusting the black level, that is, the level at which the luminance is lowest in an image to be displayed on a monitor of these apparatuses. Conventionally, in order to realize this function, a method is used to vary a γ correction voltage in a γ correction circuit. This γ correction corrects the characteristics of gradation (degree of luminance variation) of an image to linear characteristics, and use of this correction also makes it possible to adjust the black level at which the luminance is lowest.
Meanwhile, there is a case in which a blank area is displayed on an image display apparatus such as that described above so that a blanking mark indicating a photographic range of a video camera, etc., is displayed superimposed on an image. This blank area is often displayed at the black level at which the luminance is lowest. It is preferable that the black level of this blank area always be at a predetermined level without being influenced by the luminance of an image to be displayed.
However, if attempts to vary the black level by a method which uses the above-described γ correction circuit are made, since this γ correction circuit is provided immediately before a driver which drives a display mechanism, such as an LCD, and a combined image after the blank area and the image are combined together is corrected, there is a problem in that the luminances of both of the blank area and the image vary at the same time.